Selective switch



ug- 29, 1939 l E. P. G. WRIGHT t 2,170,885

SELECTIVE SWITCH Filed Nov. 28, 1936 E. G. WRIGHT Patented Aug. 29, 1939UNITED STATES 2,170,885 SELECTIVE SWITCH Esmond Philip land, assignorIncorporated, of New York Goodwin Wright, London, Engto Western NewYork, N.

Electric Company, Y., a corporation Application November 28, 1936,Serial No. 113,185

Great Britain 12 Claims.

This invention relates to selective switching mechanism and particularlyto switches of the two-motion step-b-y-step type common in automatictelephone systems.

It is the object of the invention to increase the adaptability andeiciency of two-motion switches known as the square type, that isswitches in which the brushes in their selecting and resetting movementsdescribe a closed rectangle.

In two-motion selector switches of the type in which the brushes retracetheir selective movement to reach normal position, it is usual to absorba directive set of operating impulses by releasing the shaft and returnof the brushes to l normal position immediately after the directivemovement which is to be absorbed and before another train of directiveimpulses is received. In case certain but not all directive digits areto be absorbed, the release of the brushes is effected 20 by the closureof shaft-operated springs in response to these certain digits or bymeans of an additional brush and. associated contacts. These knownmethods of digit-absorption and discrimination cannot effectively beappliedto the square g5 type of selector switch in which the releasetime may exceed the interval between succeeding trains of directiveimpulses. l

According to this invention the absorption oi a directive train ofimpulses is eiiected in a 30 two-motion switch by the storing ci a partof the impulses oi a digit train on relays, the remaining impulses inthe train being effective to advance the brushes of the selector. In thecase of im` pulse trains comprising less than a predetermined 5 numberof impulses, the absorption is effected without moving the brushes from`normal, some of the impulses of the next train of impulses beingabsorbed and the succeeding impulses being eiective to advance thebrushes in a selective moveo ment. Following a primary selectivemovement, the switch may be advanced either by a selective secondarymovement in response to another train of impulses or by an automaticsecondary movement to hunt for an idle set of terminals.

b A feature of the invention is the absorption of the initial impulsesof a second digit to extend the interval between digits artificiallywhile the brushes are being returned to normal, only the succeedingimpulses of the second digit being 50 effective to selectively positionthe brushes of the switch.

Further explanation of the invention will be made by describing oneembodiment of the invention which is shown schematically in the 55drawing which forms a part of this specification,

January 17, 1936 The invention is, of course, not limited to the specicarrangement and structure disclosed but is in general applicable to anyselective switch to effect a desired digit absorbing operation.

The drawing shows schematically a two-motion square-type selectiveswitch comprising an impulse receiving relay A, a vertical steppingmag-'l net VM, a rotary stepping magnet RM, the brushes RW, TW and VW,and the associated control relays and circuit connections.

In the drawing, capital letters are used as the reference characters forthe relays and magnets and corresponding lower case letters withnumerical subscripts` are used as the reference characters for thecontact springs. associated broken line connections may or may not beprovided depending upon the desired operation of the switch. When relayJ is not provided the contact spring b2 is connected to ground andcontact `tl is connected to contact c5 as shown by the solid lineconnections. But when relay J is provided contact spring b2 is connectedto the front contact oi spring c4 instead of being connected directly toground, and contact spring tl is connected directly to ground.

The operation of the selector switch shown in the drawing will first bedescribed assuming that relay J is not provided. Upon seizure of theselector switch and closure of the control circuit over the conductorsof line L, relay A operates, closing at contact a2 a circuit foroperating the release relay B. Relay A thereafter responds to the digitimpulses transmitted over line L. Relay B, being slow in releasing,remains operated during the response of relay The release oi relay A, inresponse to the rst impulse, closes a circuit through the back contactof spring al and contact bl for operating relay C; and relay C, beingslow in releasing, remains operated until all of the impulses in thetrain have been received. The reoperation of relay A, at the end of theiirst impulse, closes a circuit through the front contact of spring aland contacts cl and cl for energizing the left winding oi relay D. Therelease of Relay J and the relay A in response to the second impulse ofthe train closes a circuitV through the back contact of spring al,contacts bl and dl, and the right winding of relay D for holding relay Doperated; and closes a circuit through the back contact of spring alcontact bl the back contact of spring g2, front contact of spring d2,back contact of spring f2, and the upper winding of relay E foroperating relay E. Relay E opens at contact el the circuit through theleft winding of relay D so that,` upon the opening Voi the circuitthrough the right winding of relay D when relay A reoperlast impulse ofthe digit, relay C releases thereby ates at the end of the secondimpulse, relay D causing the release or relay D. Relay G does notreleases. Relay Il.' is held operated by a circuit operate since Contactn2 of the oli-normal springs through its lower winding and contacts e2and b2. is opened when the switch moves out of normal tacts or" springsg2 and d2, the back contact of the number of the level being three lessthan the numoI-normal spring nl, contact e3 and the upper ber ofimpulses in the train. That is, if the first winding of relay F foroperating relay F. Relay directive digit is 4, the brushes are steppedup to F' CIOSSS a lOCliing Circuit through its lower windthe rst levelof the terminal bank; and if the ing and CentaCtS f3 and U2. Thereoperation rst directive digit is 5, 6, 7, 8, 9 or 0, the brushes ofrelay A at the end of the third impulse closes a are stepped up to level2, 3, 4, 5, e or l. If the back Contact 0f spring 02, thenormally-closed spending to the number of impulses in the sec- COntaCtn2 0f the 01T -nOrInal Springs 0f the Switch, ond directive train. If,however, the rst directive and CentaCt 84, fOr Operating relay G- RelayG digit is 0, relay O is operated when relay C recloses at Contact g4 acircuit for operating relay leases, the circuit for operating relay Obeing H; and relay H locks through contacts h2 and b4. traced throughbrushes VW and seventh oir-nor- Witll relay G Operatedy the SeCOnd trein0f iinmal terminals ofthe associated vertical bank, and pulses inCOlnngOVer line L is eTeCtVe t0 Cause through contacts c3 and h3. Relay Ocloses a the Operatien 0f the Vertieal magnet VM and adcircuit foroperating the rotary-stepping magnet relay C releases at the end of thesecond train of an idle set 0f terminals, relay T operates. At impulses,relay G also releases; but relay H recontact ti, relay T opensy thecircuit for operating mains Operated So that. if the second digit isZero. magnet RM so as to stop the brushes of the switch the Circuit fOrOperating relay O is open at conon the rst idle set of terminals in thelevel. tact h3. The third train of directive impulses in- If now it isdesired that the switch be arcoming over line L is then effective tocause the ranged to return to normal if a particular digit Operation 0fthe rotary-stepping magnet RM and such as 8 is dialed, relay J isprovided, its windadvance ol the brushes to a corresponding set of ingbeing connected to terminal 5 of the vertical tact l, back Contacts OfSprings @"2 and d2, and tact spring tl is connected directly to ground.

first directive train of impulses iS received, relay ment of the switchresults. As soon as a train Dalso releases leal/iner the switch ready,as before, of more than three impulses is received by relay remainsoperated, during the response 0f relay A raised to level i in responseto a train of ten irnand magnet VM, Since its left Winding iSenerpulses, the operation of relay O causes the switch gized each timethe front contact of spring al to hunt for an idle set of terminals inlevel 'l closes and its right winding is energized each as hereinbeforedescribed. If the brushes are time the back contact of spring al closes.When raised to level 5 in response to a train of eight relay A remainsenergized after receiving the impulses, relay J operates when relay Creleases,

the circuit for operating relay J being traced through brushes VWandiifth ofi-normal vertical back contacts, contact c3 and contact h3.Relay J locks through contacts :il and b3. Rotary magnet RM is nowautomatically operated in a circuit through the front contact oforfnormal spring nl, contact i2, interrupter contacts of magnet RM, andthrough contacts hl and ti to ground. The brushes are advanced by magnetRM to the eleventh rotary position of level` 8 and then drop to thenormal level. When the shaft reaches normal, the circuit for operatingmagnet RM is opened at the oinormal spring ni; and the closure oioit-normal contact n3 completes a circuit, which includes contact 7'3,for operating relay H. Relay I-I locks through contacts h2 and bil. Thenext train of impulses consisting of more than three impulses iseffective to select one of tlie vertical levels l to l, inclusive, ashereinbefore described. The first three impulses of the digit areabsorbed so thatthere is amgple time cr the switch to be returned tonormal before the fourth impulse is received and the switch begins itsvertical movement. And the next succeeding train of impulses received byrelay A eiects the operation ci rotary-stepping magnet RM and advance ofthe brushes to a desired set of terminals in the selected level.

If, instead of absorbing the digit 8, it is desired that there be bothselective and hunting movements on level 5, relay J is provided butcontact spring ti is not connected to ground. In this case brush RW isused to effect the advance of the brushes over any selected group ofterminals in level 5 until an idle set of terminals is engaged or thelast set o-i terminals in the group is reached. When relay J operates,magnet RM` is connected through contacts nl, i2, interrupter contacts ofmagnet RM, contacts hl, ti and c5 to brush RW; but, the normal terminalbeing free of ground potential, magnet RM is not operated until relay Aresponds to the next set of digit impulses. The operation of magnet RMin response to these impulses advances the brushes to the rst terminalor the desired group in level t; whereupon, when relay C releases,magnet RM is operated through brush RW and the grounded terminals oi thegroup. Relay J being operated the test circuit through relay T and brushTW is closed at contact it so: that relay T operates as soon as an idleset of terminals is reached. Ii the brushes are advanced to the last setof terminals in the selected group, magnet RM cannot again reoperatesince brush RW finds no ground potential on the last terminal of agroup.

Other variations and modifications of the switch may be made withoutdeparting from the spirit of the invention.

What is claimed is:

l. In an automatic telephone system, a selector switch comprising a setof brushes, a bank of terminals, and a stepping magnet for advancing thebrushes, an imrpulse relay associated with said switch for receivingdirective impulses from subscribers impulse senders, circuit meanscontrolled by said relay in response to a train oi more than a certainnumber of impulses from` a subscribers impulse sender for absorbing saidcertain number of the impulses without movement oi the brushes and foroperating said magnet in response to the succeeding impulses of thetrain to eiiect a desired selective movement of the brushes.

2. In a combination according to claim l, circuit mleans renderedeffectiveafter receipt of a first train of impulses by said impulserelay for preventing the absorption of any impulse of the next trainreceived by said impulse relay.

3. In combination, a selector switch comprising a vertical-steppingmagnet, a rotary-stepping magnet, a set of' brushes and an associatedbank of terminals, an impulse relay responsive to directive impulses,circuit means controlled by said impulse relay for absorbing one or moreimpulses of a train received by said impulse relay without movement ofthe switch out of normal position and effective in response tosucceeding impulses in the same train for causing the operation of saidvertical-stepping magnet to select a desired level of the terminal bank,and circuit means including said rotary-stepping magnet eiective inresponse to the next succeeding train of impulses received by saidimpulse relay to select a desired set of terminals in the selectedlevel.

1i. In combination, a selector switch comprising a stepping magnet, aset of brushes and an associated bank of terminals, an impulse relayresponsive to directive impulses, circuit means controlled by saidimpulse relay for absorbing a rst train or impulses of not more than apredetermined number o like directive impulses without movement oi thebrushes of the switch and for absorbing said predetermined number ofimpulses of a train consisting of more than said predetermined number oflike directive impulses and for causing the operation of saidverticalstepping magnet in response to the succeeding irnpulses in thetrain, and circuit means effective ii no movement of the switch resultsfrom the rst train of impulses received by said impulse relay forcausing the operation oi said verticalstepping magnet in response to thenext succeeding train of impulses received by said impulse relay.

5. In combination, a selector switch comprising a vertical-steppingmagnet, a rotary-stepping magnet, a set of brushes and an associatedbank of terminals, an impulse relay responsive to directive impulses,circuit means controlled by said impulse relay for absorbing a firsttrain of irnpulses of not more than a predetermined number or impulseswithout movement of the brushes ofthe switch and for absorbing saidpredetermined number of impulses of a train consisting of more than saidpredetermined number oi irnpulses and for causing the operation of saidvertical-stepping magnet in response to the suc- '1 ceeding impulses inthe train, circuit means eifective if no movement of the switch resultsfrom the iirst train of impulses received by said impulse relay forcausing the operation of said vertical-stepping magnet in response tothe second succeeding train of impulses received by said impulse relay,and circuit means effective in response to the first train of impulsesreceived by said impulse relay following a vertical movement of thebrushes for causing the operation of said rotary-stepping magnet.

6. In a combination according to claim 5, circuit means efiective if thelevel selected by the vertical movement oi the switch is a particularlevel for rendering the rotary-stepping magnet automatically operativeto advance the brushes to hunt for an idle set of terminals in theselected level.

7. In a combination according to claim 5, circuit means effectivefollowing a directive rotary lay, circuit means including saidrotary-stepping magnet for thereupon advancing the brushes automaticallybeyond selected level to cause the return of the brushes to normalposition, and circuit means for absorbnormal position before thevertical-stepping magnet is again operated.

10. In a selector switch having a primary magcertain number.

l1. In a selector switch rcuit ESMOND PHILIP GOODWIN WRIGHT.

